Apparatus and methods for treating congestive heart disease

ABSTRACT

Methods and apparatus are provided for treating congestive heart by actively or passively enhancing perfusion to the renal arteries. A first embodiment comprises a specially configured balloon catheter and extracorporeal pump, wherein the pump operates in a “once-through” fashion or alternating volume displacement mode. In another embodiment the catheter includes a pair of balloons to isolate a region of the aorta, and a third balloon that directs flow into the renal arteries. In still further embodiments, a stent or cuff having a constricted region is deployed in or around the aorta, respectively, to create a backpressure upstream of the stent or cuff. Methods of enhancing renal perfusion also are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of copending U.S. patentapplication Ser. No. 09/562,493 filed on May 1, 2000, incorporated byreference herein, which is a continuation in part of copending U.S.patent application Ser. No. 09/229,390 filed on Jan. 11, 1999,incorporated by reference herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not Applicable

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

[0003] Not Applicable

BACKGROUND OF THE INVENTION

[0004] Acute renal failure (“ARF”) is an abrupt decrease in the kidney'sability to excrete waste from a patient's blood. This change in kidneyfunction may be attributable to many causes. A traumatic event, such ashemorrhage, gastrointestinal fluid loss, or renal fluid loss withoutproper fluid replacement may cause the patient to go into ARF. Patient'smay also become vulnerable to ARF after receiving anesthesia, surgery,α-adrenergic argonists or high dose dopamine or patients withhepatorenal syndrome because of related systemic or renalvasoconstriction. Alternatively, systemic vasodilation cause byanaphylaxis; antihypertensive drugs, sepsis or drug overdose may alsocause ARF because the body's natural defense is to shut down“non-essential” organs such as the kidneys. Additionally, reducedcardiac output caused by cardiac shock, congestive heart failure,pericardial tamponade or massive pulmonary embolism creates an excess offluid in the body. Specifically it has long been known that cardiacdysfunction induces a series of events that ultimately contribute tocongestive heart failure (“CHF”). One such event is a reduction in renalblood flow due to reduced cardiac output. This reduced flow can in turnresult in the retention of excess fluid in the patient's body, leadingfor example, to pulmonary and cardiac edema.

[0005] The appearance of ARF significantly increases mortality. ICUpatients mortality rates for patients without ARF are approximately 20%.However, once ARF is achieved, the mortality rates jump to between 60%and 80%. Preventing ARF in patients at risk but who have not yet had anyrenal insufficiency will have a dramatic impact on ICU mortality rates.

[0006] Chapter 62 of Heart Disease: A Textbook of CardiovascularMedicine, (E. Braunwald, ed., 5th ed. 1996), published by Saunders ofPhiladelphia, Pa., reports that for patients with CHF, the fall ineffective renal blood flow is proportional to the reduction in cardiacoutput. Renal blood flow in normal patients in an age range of 20-80years averages 600 to 660 ml/min/m² corresponding to about 14 to 20percent of simultaneously measured cardiac output. Within a widespectrum of CHF severity, renal blood flow is depressed to an averagerange of 250 to 450 ml/min/m².

[0007] Previously known methods of treating ARF attributable tocongestive heart failure and deteriorating renal function in patientshaving CHF principally involve administering drugs, including diureticsthat enhance renal function, such as furosemide and thiazide;vasopressors intended to enhance renal blood flow, such as Dopamine; andvasodilators that reduce vasoconstriction of the renal vessels. Many ofthese drugs, when administered in systemic doses, have undesirableside-effects. Additionally, many of these drugs would not be helpful intreating other causes of ARF. Specifically, administering vasodilatorsto dilate the renal artery to a patient suffering from systemicvasodilation would merely compound the vasodilation system wide.

[0008] In addition, for patients with severe CHF (e.g., those awaitingheart transplant), mechanical methods, such as hemodialysis or leftventricular assist devices, may be implemented. Mechanical treatments,such as hemodialysis, however, generally have not been used forlong-term management of CHF. Such mechanical treatments would also notbe help for patients with strong hearts suffering from ARF.

[0009] Advanced heart failure (“HF”) requires the combination of potentdiuretics and severe restriction of salt intake. Poor patient complianceis a major cause of refractoriness to treatment. On the other hand, asrenal urine output decreases with reduced renal perfusion, in the eventof dehydration, the required diuretic dosages increase.

[0010] Recent work has focused on the use of intra-aortic balloon pumps(IABPs) to divert blood flow into the renal arteries. One such techniqueinvolves placing an IABP in the abdominal aorta so that the balloon issituated slightly below (proximal to) the renal arteries. The balloon isselectively inflated and deflated in a counterpulsation mode so thatincreased pressure distal to the balloon directs a greater portion ofblood flow into the renal arteries.

[0011] In view of the foregoing, it would be desirable to providemethods and apparatus for treating and managing ARF withoutadministering high doses of drugs or dehydrating the patient.

[0012] It further would be desirable to provide methods and apparatusfor treating and managing ARF by improving blood flow to the kidneys,thereby enhancing renal function. Specifically, a system which could beused for all ARF patients during critical treatment times would bebeneficial. In particular, a system which could be placed easily in apatient during emergency or critical care without the need for surgeryor X-ray fluoroscopy guidance would be useful to all patients in dangerof ARF.

[0013] It also would be desirable to provide methods and apparatus fortreating and managing ARF that permit the administration of low doses ofdrugs, in a localized manner, to improve renal function without havingan effect system wide.

[0014] It still further would be desirable to provide methods andapparatus for treating and managing ARF using apparatus that may bepercutaneously and transluminally implanted in the patient.

SUMMARY OF THE INVENTION

[0015] The present invention provides methods and apparatus for treatingand managing ARF without administering high doses of drugs ordehydrating the patient by improving blood flow to the kidneys, therebyenhancing renal function.

[0016] This invention also provides methods and apparatus for treatingand managing ARF that permit the administration of low doses of drugs,in a localized manner, to improve renal function.

[0017] The present invention also provides methods and apparatus fortreating and managing ARF using apparatus that may be percutaneously andtransluminally implanted in the patient.

[0018] These and other advantages of the present invention are obtainedby providing apparatus and methods that either actively or passivelyenhance perfusion of the renal arteries with autologous blood. Activeperfusion may be accomplished using an extracorporeal pump and one of anumber of specially designed catheter sets, while passive perfusion maybe accomplished by creating a constriction in the aorta proximal to therenal arteries. Apparatus and method which direct a low dose of drugs ina localized manner are also provided.

[0019] To facilitate the advancement of the catheter into the patient'scoronary artery, a guiding catheter having a distal tip may be firstpercutaneously introduced into the abdominal aorta of a patient by theSeldinger technique through the brachial or femoral arteries. Thecatheter is advanced until the preshaped distal tip of the guidingcatheter is disposed within the aorta adjacent the ostium of the renalarteries. A balloon catheter embodying features of the invention maythen be advanced through the guiding catheter into the patient'sabdominal aorta over a guidewire until the balloon on the catheter isdisposed at the desired region of the patient's artery. In specificembodiments, the use of a guiding catheter is unnecessary. Theadvancement of the catheter over a guidewire is sufficient to achieveadequate placement.

[0020] For active perfusion, the apparatus of the present inventionpreferably comprises a balloon catheter coupled to a pump. The pump maybe extracorporeal or in-line. In one embodiment the catheter has aninlet end configured for placement in a source of arterial blood, suchas the aorta or a femoral artery, and an outlet end configured toprovide perfusion of one or both renal arteries. Blood is drawn throughthe catheter from the inlet end and pumped back, using either the sameor a different lumen, to one or both renal arteries. Blood drawn intothe catheter either may pass through the extracorporeal pump, oralternatively the pump may operate by periodic fluid displacement.Sensors may be provided on the catheter to monitor pressure within therenal arteries, and such pressure data may in turn be used to adjust thepump operation. The balloon catheter has at least one balloon. Inspecific embodiments, the balloon catheter has 2 balloons. The balloonsmay be systematically inflated against the aorta wall and deflated toassist in the perfusion of the renal arteries.

[0021] The balloon may be formed using either compliant or non-compliantmaterials, preferably compliant. Most optimally, the balloon material ischosen so that inflation of the balloon to a volume sufficient toocclude the aorta, i.e., to a diameter of between 15 and 35 mm, willcreate a sufficient pressure within the balloon so as to provide theballoon with some degree of mechanical rigidity and to likewise apply asmall amount of outward radial force to the aortic wall so as to providepositional and orientational stability to the balloon. Such a pressureis typically between about 4 and about 20 psi. Materials that canachieve such behavior include synthetic polyisoprene and thermoplasticurethane. Material durometer and tensile modulus must be selectedappropriately so as to allow for the above properties to be exhibitedwith a practical balloon-wall thickness. Material with a shore hardnessof about 70A to about 100A, preferably about 80A to about 90A areappropriate. For example, thermoplastic urethane such as Dow Pellethane2363-80A, which has a Shore hardness of 80A, a tensile modulus of 1750psi at 300% elongation and an ultimate elongation of 550%, can be usedfor forming the balloon. Balloons may be formed by dipping a shapedmandrel into a mixture of urethane dissolved in a solvent, such astetrahydrofuran. The mandrel should be shaped so as to produce anuninflated balloon with a diameter of between 3 and 8 mm. The dippingprocess should be repeated so as to produce a balloon with an uninflatedwall thickness of between 0.002 in. and 0.010 in. Alternatively, theballoon can be formed by first melt-extruding a length of tubing andthen blow-molding the tube into a balloon form. Dimensions of the tubingand mold would be chosen to achieve the same diameter and thicknessdescribed above.

[0022] The inflated balloon should have a maximum safety-factoreddiameter of between 15 and 35 mm, to accommodate the range of diametersof the human infrarenal aorta. Alternatively, the device could beavailable in a range of balloon sizes, such as 15 to 25 mm and 25 to 35mm. In order to provide positional and orientational stability to thecatheter within the aorta, the inflated balloon should have a length ofabout 2 to about 8 cm, preferably about 3 to about 6 cm. The cathetershaft can be formed by melt extrusion processing of thermoplasticpolymers typically used in catheters, such as Hytrel, Pebax orpolyurethane.

[0023] The balloon can be attached to the catheter shaft by either anadhesive bond or a thermal fusion. The later can be used if athermoplastic balloon material, such as polyurethane, is used. If athermoset material, such as polyisoprene, is used, an adhesive will beused to attach the balloon. Cyanoacrylate adhesives, such as Loctite4203 combined with Loctite Primer 770, can be used, as canurethane-based UV-cured adhesives, such as Dymax 205CTH can also beused. In addition, 2-part adhesives, such as epoxies or urethane-basedadhesives can be used.

[0024] In a specific embodiment, the catheter has a pump which is anin-line archimedean screw pump situated within a balloon catheter. Anarchimedean screw is a screw which allows for fluid movement with theturning of the screw. The balloon catheter has 2 balloons, a distalballoon and a proximal balloon, longitudinally displaced from eachother, and the screw pump is preferably situated between the twoballoons. However, the screw pump may also be situated at a locationdistal to the distal balloon. The catheter is placed in the patientwithin the abdominal aorta. The balloon catheter has a proximal end anda distal end. The catheter distal end is inserted below the renalarteries, specifically the femoral artery, in the patient and advanceduntil the distal balloon is situated above the renal arteries. Below therenal arteries is defined as toward the patients legs, and above isdefined as toward the patient's head. However, in certain embodiments,it may be preferable to enter the patient from above the renal arteries,for example from the brachial arteries. If so, then the placement of theballoons and any blood or drug outlet ports would be inverted on thecatheter shaft with respect to any description of preferred embodimentsin this application. A blood inlet is located on a portion of thecatheter distal end that is distal to the distal balloon. In thespecific embodiment, the screw pump is activated, causing blood to enterthe catheter through the blood lumen. The screw pump causes a pressureincrease in the blood, which then exits the catheter through outletports near the renal arteries. Alternatively, some blood may exit thecatheter at the proximal end to provide blood to the lower extremities.The balloons may be inflated and deflated to provide blood flow to thepatient's lower extremities.

[0025] The balloon of the catheter is inflated to retain the outlet endof the catheter in position in a renal artery and to prevent backflow ofblood into the abdominal aorta. Alternatively, a pair of balloons may beselectively inflated to isolate the region of the abdominal aortaadjacent to the renal arteries. In yet another embodiment, a centerballoon is disposed within an isolated region of the abdominal aortadefined by the distal and proximal balloons, and the extracorporeal pumpis employed to inflate the third balloon to increase flow to the renalarteries.

[0026] In any of the foregoing cases it is expected that blood passingthrough the catheter, or trapped within the isolated region of theabdominal aorta, will have a higher pressure and flow rate than bloodreaching the renal arteries via the abdominal aorta. This, in turn, isexpected to improve renal blood flow without the administration ofsystemic drug doses. The enhanced renal blood flow is expected toprovide a proportional increase in renal function, thereby reducingfluid retention.

[0027] In further alternative embodiments, the catheter may include adrug infusion reservoir that injects a low dose of a drug (e.g., adiuretic or vasodilator) into blood flowing through the lumen, so thatthe drug-infused blood passes directly into the kidneys, or separatecatheters to perfuse the left and right kidneys independently.

[0028] In a specific embodiment, a balloon catheter having a distal endand a proximal end and at least one lumen therebetween is inserted in apatient below the renal arteries, specifically the femoral artery. Thecatheter includes a balloon disposed about the catheter shaft. Thecatheter is advanced until the distal end sits above the renal arteriesand the balloon sits at a location below the renal arteries within thepatient's abdominal aorta. A drug delivery device is connected to theproximal end of the catheter. The drug delivery device may beextracorporeal or in-line. In specific embodiments, the catheter has atleast two lumens. One lumen is an inflation lumen, in fluidcommunication with the interior of the balloon. The second lumen is andrug delivery lumen, which is in fluid communication with the drugdelivery device and with discharge ports which are located on thecatheter shaft at a location distal to the balloon. In some embodiments,a third lumen may exist, which is the blood lumen. The blood lumen wouldhave an inlet port on the catheter shaft distal end and an outlet portat a location proximal to the balloon.

[0029] After placement, the balloon is inflated. When the balloon isinflated against the abdominal aorta wall, the drug delivery device isactivated. A drug is delivered through the drug delivery lumen, and thedrug enters the patients aorta through the discharge points. Because ofthe inflated balloon sitting just below the renal arteries, the drug iseffectively blocked from entering the lower extremities, and insteadflows to the renal arteries. In certain embodiments, the drug isdelivered in a pulse fashion, with the balloon inflating at drugdelivery and deflating to allow blood to flow between drug deliverypulses.

[0030] For passive perfusion, apparatus is provided that constricts theabdominal aorta proximal to the renal arteries. In this case, a stent orother device is disposed within the aorta to cause a narrowing of theaorta proximal to the renal arteries, thereby creating a pressuredifferential across the apparatus that is expected to improve blood flowrate to the renal arteries.

[0031] Methods of using the apparatus of the present invention fortreating ARF are also provided.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Further features of the invention, its nature and variousadvantages will be more apparent from the accompanying drawings and thefollowing detailed description of the preferred embodiments, in which:

[0033]FIG. 1 is a partial sectional view of a human circulatory systemhaving perfusion apparatus constructed in accordance with the principlesof the present invention implanted therein;

[0034]FIGS. 2A and 2B are, respectively, a side view of the distal endof the apparatus of the apparatus of FIG. 1, and a cross-sectional viewof the apparatus along section line 2B-2B of FIG. 2A;

[0035]FIG. 3 is a partial sectional view of a human circulatory systemhaving an alternative embodiment of the apparatus of FIG. 1 including adouble balloon for simultaneous perfusion of both renal arteries;

[0036]FIG. 4 is a partial sectional view of a human circulatory systemhaving an alternative embodiment of the apparatus of FIG. 1 in whichcatheter blood flow occurs in one lumen;

[0037]FIG. 5 is a partial sectional view of a human circulatory systemhaving an alternative embodiment of the apparatus of FIG. 3 in whichcatheter blood flow occurs in one lumen;

[0038]FIG. 6 is a partial sectional view of a human circulatory systemhaving an alternative embodiment of the apparatus of FIG. 1 in whichblood is pumped using periodic fluid displacement;

[0039]FIG. 7 is a partial sectional view of a human circulatory systemhaving an alternative embodiment of the apparatus of FIG. 3 whichperfuses both renal arteries;

[0040]FIG. 8 is a partial sectional view of a human circulatory systemhaving an alternative embodiment of the apparatus of the presentinvention implanted therein;

[0041]FIGS. 9A and 9B are partial sectional views of the distal end ofapparatus labeled with radiopaque markers in, respectively, the inflatedand deflated states; and

[0042]FIGS. 10A and 10B are partial sectional views of a humancirculatory system having, respectively, an aortic stent and aninflatable cuff placed proximal of the renal arteries to enhanceperfusion.

[0043]FIG. 11 is an elevational view of a catheter partially in sectionof a catheter embodying features of the invention including anarchimedean screw pump disposed with a patient's abdominal aorta.

[0044]FIG. 12 is an elevational view partially in section of a catheterembodying features of the invention including an archimedean screw pump.

[0045]FIG. 13 is an elevational view of an archimedean screw.

[0046]FIG. 14 is an elevational view, partially in section, of analternative embodiment of the catheter of the invention including thearchimedean screw pump.

[0047]FIGS. 15A, 15B and 15C are transverse cross sectional views of thecatheter of FIG. 12 along lines 15A-A, 15B-B and 15C-C respectively.

[0048]FIG. 16 is an elevational view of a catheter embodying features ofthe invention including a drug delivery system disposed with a patient'sabdominal aorta, FIG. 16B is an enlarged view of area 16B.

[0049]FIG. 17 is an elevational view of an alternative embodiment of acatheter embodying features of the invention including a drug deliverysystem.

[0050]FIG. 18 is a transverse cross sectional view of the catheter ofFIG. 16 along line 18-18.

[0051]FIG. 19 is an alternative transverse cross sectional view of thecatheter of FIG. 16 along line 18-18.

[0052]FIG. 20 is a graphical representation of the balloon inflation anddeflation during drug infusion and the drug's affect on the renalarteries.

DETAILED DESCRIPTION OF THE INVENTION

[0053] The present invention provides several apparatus for treatingpatients suffering from congestive heart failure (“CHF”) by improvingrenal blood flow and renal function. Some preferred embodiments of thepresent invention provide active perfusion of the renal arteries, andcomprise a catheter and an extracorporeal pump. The catheter and pumpmay be used either to withdraw autologous blood from the patient's bodyand reperfuse that blood into the patient's renal arteries, or toisolate a region of the abdominal aorta and cause a pressuredifferential within-the isolated region that causes perfusion of therenal arteries.

[0054] Other preferred embodiments of the present invention cause aconstriction in the abdominal aorta downstream (proximal) of the renalarteries, so that the pressure differential resulting from theconstriction preferentially perfuses the renal arteries.

[0055] Referring to FIGS. 1 and 2A-2B, a first illustrative embodimentof an active perfusion apparatus of the present invention comprisingcatheter and blood pump 36 is described.

[0056] Catheter 30 comprises a hollow flexible tube having inlet port31, outlet port 33, and balloon 32. Ports 31 and 33 may optionallyinclude one-way valves, such as duckbill valves, that control thedirection of flow. As shown in FIG. 2B, catheter 30 includes inlet lumen38, outlet lumen 39 and inflation lumen 40. Catheter 30 preferablycomprises a flexible biocompatable material typically used in catheterconstruction, such as polyethylene, polyurethane or nylon.

[0057] Balloon 32, which is configured to retain distal end 41 ofcatheter 30 in renal artery RA, is inflated and deflated using aninflation medium, e.g., saline, supplied by inflation device 34 throughinflation lumen 40. Balloon 32 preferably comprises a compliantbio-compatible material, such as nylon. Inflation device 34 preferablycomprises, e.g., a syringe, a pressurized cylinder or a pump.

[0058] Blood pump 36 is coupled in-line with catheter 30, and includespump 36 a driven by variable speed motor 36 b. Blood pump 36 maycomprise any of a number of previously known devices, such as a rollerpump, centrifuge pump, or positive-displacement type pump. Blood pump 36may in addition include control circuitry that receives signals fromsensors disposed in catheter 30 to monitor local pressures, for example,renal and aortic pressure. Such monitored values may then be used by thecontrol circuitry to adjust the perfusion pressure, blood flow rate orpump speed used to perfuse the kidneys.

[0059] Catheter 30 also optionally comprises a blood oxygenation element42 disposed within the extracorporeal blood circuit. Oxygenation element42, if provided, supplies oxygen to oxygen-poor blood prior to perfusioninto renal artery RA. Oxygenation element 42 may comprise, for example,a blood oxygenator such as used in cardiopulmonary bypass.Alternatively, the blood perfused into the renal artery may be mixedwith saline supersaturated with oxygen, for example, as described inU.S. Pat. No. 5,797,876, which is incorporated herein by reference.

[0060] In operation, blood enters catheter 30 through inlet port 31 andis drawn out of the patient's body through inlet lumen 39 to inlet tube35 of pump 36. The blood then passes through blood pump 36, whichcontrols the volume and pressure of blood delivered to the renal artery.Blood then passes through pump outlet tube 37, back through outlet lumen39 of catheter 30, and is delivered to the renal artery through outletport 33. As described hereinabove, operation of the blood pump may beadjusted responsive to pressure or flow parameters measured in the renalarteries, the aorta, or elsewhere within catheter 30.

[0061] Catheter 30 preferably is implanted in circulatory system C sothat inlet port 31 is disposed in abdominal aorta AA, while outlet port33 is disposed in renal artery RA. When balloon 32 inflates, it engagesthe walls of the renal artery and retains holes 31 and 33 in position.Balloon 32 also prevents backflow of high pressure blood exiting throughoutlet port 33 from flowing backwards into abdominal aorta AA.Accordingly, blood entering catheter 30 via inlet port 31 passes intothe renal artery RA and kidney K through outlet port 33, therebyenhancing renal blood flow and renal function.

[0062] Referring now to FIG. 3, an alternative embodiment of the activeperfusion apparatus of the present invention, comprising catheter 50 andpump 36, is described. Catheter 50 is similar in construction tocatheter 30 of FIGS. 1 & 2A-2B, and includes inlet lumen 38, outletlumen 39, and inflation lumen 40. Catheter 50 is coupled to ballooninflation device 34, blood pump 36, including pump inlet tube 35 andpump outlet tube 37. Unlike catheter 30, however, distal region 56 ofcatheter 50 is disposed in the abdominal aorta, not the renal artery,and catheter 50 includes proximal balloon 53 in addition to balloon 52located between inlet port 51 and outlet port 54.

[0063] In particular, inlet port 51 is disposed in distal region 56 ofcatheter 50, and again may optionally include a one-way flow valve.Outlet port 54 comprises several apertures communicating with outletlumen 39, and may in addition optionally include one-way flow valves.The positions of the apertures forming outlet port 54 between balloons52 and 53 and adjacent renal arteries RA ensures that the blood isdeposited into both kidneys simultaneously, thereby enhancing renalblood-flow and function.

[0064] Balloons 52 and 53 are inflated/deflated with an inflationmedium, such as saline, using inflation device 34. When inflated,balloons 52 and 53 isolate the region of the aorta there between(including the renal arteries) from the remainder of the aorta.Consequently, blood exiting catheter 50 via outlet port 54 is directedinto renal arteries RA. In addition, because for this embodimentinflation of the balloons 52 and 53 occludes blood flow to the patient'slower extremities, balloons 52 and 53 must be periodically deflated.Accordingly, inflation device 34 preferably comprises a pump thatdeflates balloons 52 and 53 at predetermined intervals, or issynchronized to the patient's heart rhythm via controller 55. In thelatter case, controller 55 may comprise, for example, a previously knownEKG device or blood oximeter.

[0065] In operation, catheter 50 is percutaneously and transluminallyintroduced in the patient's abdominal aorta via a cut-down to thefemoral artery. Once catheter 50 is disposed so that balloons 52 and 53straddle renal arteries RA, the balloons are inflated by inflationdevice 34. When inflated, the balloons hold inlet port 51 and outletport 54 in position within aorta AA. The balloons also serve to preventhigh pressure blood exiting through outlet port 54 from flowing out ofthe isolated region into other regions of the aorta. Blood pump 36 pumpsblood through the fluid circuit from inlet port 51 to outlet port 54.Periodically, e.g., every 15 seconds, balloons 52 and 53 are deflated toreestablish blood flow to the lower extremities for a short period oftime to prevent ischemia of the lower limbs.

[0066] Alternatively, balloons 52 and 53 may be connected to separateinflation lumens. In this embodiment, balloon 52 completely occludesaorta AA while balloon 53 is only partially inflated, thereby permittingsome flow to the lower extremities during perfusion of the kidneyswithout periodic deflation of the balloons. Alternatively, balloon 53may periodically be inflated/deflated to completely or partially occludeaorta AA independently of balloon 52.

[0067] Referring now to FIG. 4, a further alternative embodiment of anactive perfusion apparatus is described that utilizes a single lumen forblood flow. Catheter 60 is similar in construction to catheter 30 ofFIGS. 1 & 2A-2B and is coupled to inflation device 34 and blood pump 36,including pump inlet tube 35 and pump outlet tube 37. Because catheter60 provides a “once-through” flow path, it includes only a single bloodflow lumen and inflation lumen (thereby omitting, for example, outletlumen 39 of FIG. 2B).

[0068] In particular, catheter 60 includes inlet line 63 having inletport 61, and outlet line 64 having outlet port 62. Inlet line 63 iscoupled to pump inlet pump 35, while outlet line 64 is coupled to pumpoutlet tube 37. Balloon 65 is disposed on outlet line 64, is configuredto engage and retain outlet port 62 in renal artery RA, and is inflatedwith inflation medium injected via inflation device 34.

[0069] In operation, inlet line 63 is inserted into the patient'sfemoral artery, and outlet line then is inserted percutaneously andtransluminally into aorta AA via a cut-down in the contralateral femoralartery. Balloon 65 is inflated to engage the walls of renal artery RA,retain outlet port 62 in position, and prevent backflow 6 f highpressure blood into abdominal aorta AA. When blood pump 36 is activated,blood flows into inlet port 61, through inlet line 63 and pump inlettube 35 to pump 36, and is returned by pump 36 through pump outlet tube37, outlet line 64 and outlet port 62 into renal artery RA. Accordingly,blood entering catheter 60 via inlet port 61 passes into the renalartery RA and kidney K through outlet port 62, thereby enhancing renalblood flow and renal function.

[0070] Alternatively, inlet line 63 and outlet line 64 may be insertedin the same femoral artery. Also, the inlet and outlet lines may beincorporated into one concentric device. For example, a 9 Fr. pumpingcatheter may lie in the lumen of a 12 Fr. sheath; blood is pumped out ofthe body in the space between the catheter and the sheath and pumpedback through the catheter. Additionally, blood may be removed from avein instead of an artery. In this case, the venous blood may beoxygenated using an oxygenation element as described hereinabove withrespect to FIG. 1. Temperature regulation also may be performed prior toblood perfusion into renal artery RA.

[0071] With respect to FIG. 5, a further embodiment of an activeperfusion apparatus of the present invention is described. Catheter 70of FIG. 5 combines elements of catheters 50 and 60. Like catheter 50,catheter 70 employs balloons 52 and 53 controlled by balloon inflationdevice 34 to periodically isolate a region of the abdominal aorta,including the renal arteries, to permit selective perfusion of the renalarteries. Like catheter 60, catheter 70 includes separate inlet andoutlet lines and provides a “once-through” flow path. In particular,blood flows into inlet port 71 of inlet line 73, illustratively placedin the subclavian artery and extending into the aortic arch, throughpump inlet tube 35 and to blood pump 36. The blood then is pumpedthrough pump outlet tube 37, outlet line 74 and into renal arteries RAvia outlet port 72. As opposed to catheter 60, in which the blood inletis disposed in the femoral artery, inlet port 71 is instead placed inthe aortic arch because the femoral arteries are occluded duringinflation of balloons 52 and 53.

[0072] As will be obvious to one skilled in the art, catheters 60 & 70may alternatively withdraw blood from other sources than thoseillustrated in FIGS. 4 & 5. They may alternatively withdraw blood from adifferent artery or a different location in the preferred artery. Venousblood perfused in conjunction with saline supersaturated with oxygen orpassed through an external oxygenator may also be used.

[0073] Referring to FIGS. 6 and 7, still further embodiments of activeperfusion systems of the present invention are described, in which bloodis pumped using a periodic displacement method, and no blood is cycledout of the body. Catheter 100 includes balloon 32 coupled to inflationdevice 34. Catheter 120 includes balloons 52 and 53 coupled to inflationdevice 34.

[0074] Each of catheters 100 and 120 are coupled to extracorporeal pump110, which causes active perfusion of one or both renal arteries asfollows. Pump 110 includes shaft 111 having piston 111 a disposed incylinder 112 and piston 111 b disposed in cylinder 115. Piston 111 a isdisplaced by pressurized gas or liquid introduced into cylinder 112through ports 113 and 114 in an alternating fashion. This, in turn,displaces the shaft 111 and piston 111 b in cylinder 115. Cylinder 115is connected to catheter 100 by connector tube 116.

[0075] With piston 111 a in its most distal stroke position withincylinder 112 (in direction B), catheter 100 and tube 116 are initiallyprimed with saline solution, so that catheter 100 is initially filledwith saline. As pistons 111 a and 111 b are displaced proximally (indirection A) by the introduction of a pressurized gas or fluid throughport 113, movement of piston 111 b in direction A causes suction withinthe saline-filled blood lumen of catheter 100 that draws blood throughone-way inlet hole 101 and into the blood lumen. When piston 111 b isdisplaced in direction B by the introduction of a pressurized gas orfluid through port 114, the blood is forced out of one-way outlet hole102 and into the renal artery. In this manner, renal perfusion isachieved without removing blood from the patient's body.

[0076] In FIG. 6, if inlet port 101 and outlet port 102 each includeone-way valves, catheter 100 may uses single lumen for blood flow, withoperation of pump 110 causing a reversal of flow in the lumen when thedirection of piston 111 b reverses. As for the previous embodiments,catheter 100 is disposed in circulatory system C so that inlet port 101is disposed in abdominal aorta AA, while outlet port 102 is disposed inrenal artery RA. Balloon 32 is inflated by inflation device 34 to engagethe walls of the renal artery and retain port 102 in position.

[0077] Likewise, catheter 120 of FIG. 7 also may employ a single bloodlumen and one-way valves on the inlet and outlet ports, rather thanseparate blood inlet and outlet lumens. Operation of catheter 120,including cyclic inflation and deflation of balloons 52 and 53, isotherwise as described hereinabove with respect to catheter 50 of FIG.3.

[0078] Each of catheters 30, 50, 60, 70, 100, and 120 further optionallyinclude a side port (not shown) for coupling the catheter to a druginfusion device, which periodically infuses low doses of therapeuticagents into blood flowing through the catheter. Because the infuseddrugs are delivered directly into the kidneys, smaller doses may beemployed, while achieving enhanced therapeutic action and fewerside-effects.

[0079] In FIG. 8, a further alternative embodiment employing anextracorporeal pump is described. Catheter 130 comprises occlusionballoons 131 and 132 disposed on either side of center balloon 133, pump134, valve 135, controller 136 and inflation tubes 137 and 138. Valve135 selectively couples inflation tube 137 and balloons 131 and 132 topump 134 to inflate and deflate balloons 131 and 132, or couplesinflation tube 138 to pump 134 to inflate and deflate center balloon133.

[0080] Each of balloons 131-133 are made of a compliant material, suchas polyurethane. Balloons 131 and 132 are spaced apart along catheter130 so that when the catheter is placed in the abdominal aorta, theballoons straddle the renal arteries, i.e., balloon 131 is disposedabove the renal arteries and balloon 132 is disposed below. When fullyinflated, balloons 131 and 132 occlude the aorta and isolate the regionbetween the balloons from the proximal and distal portions of the aorta.Balloon 133 is disposed on catheter 130 between balloons 131 and 132 sothat it spans the section of AA that branches into the renal arteries.

[0081] Catheter 130 includes at least a first inflation lumen thatcommunicates with balloons 131 and 132, and inflation tube 137, and asecond inflation lumen that communicates with center balloon 133 andinflation tube 138. Valve 135 is coupled to inflation tubes 137 and 138to alternately inflate balloons 131 and 132, or center balloon 133,responsive to controller 136. In particular, controller 136 may beconfigured to inflate and deflate balloons 131 and 132 at a firstpredetermined time interval, and to inflate and deflate center balloon133 at a second predetermined time interval. Alternatively, controllermay be actuated responsive to the patient's heart rhythm, as determined,for example, by an EKG monitor or blood oximeter.

[0082] In operation, catheter 130 is percutaneously and transluminallyinserted into a patient's abdominal aorta via a cut-down to the femoralartery. Catheter 130 is disposed, using for example, radiopaque bandsnear balloons 131-133 visualized under a fluoroscope, so that balloons131 and 132 are on opposite sides of the junction to the renal arteries.Controller 136 is then actuated to cause valve 135 to couple inflationtube 137 to balloons 131 and 132, thereby inflating those balloons toisolate a region of the abdominal aorta. This in turn traps an amount ofblood between balloons 131 and 132 in abdominal aorta AA.

[0083] Controller 136 then actuates valve 135 to couple center balloon133 to pump 134 via inflation tube 138. Inflation of center balloon 133forces the trapped blood out of abdominal aorta AA into renal arteriesRA. All three balloons are then deflated, and the process is repeated.In this manner, renal blood flow and function is enhanced.

[0084] With reference to FIGS. 9A-9B, a further feature of the presentinvention is described. As will be apparent to those skilled in the artof interventional procedures, precise monitoring and control of theinflation and deflation of the intra-aortic balloons is critical to theefficacy of devices that utilize them. FIGS. 9A and 9B depict balloon150, which may correspond, for example, to balloon 52 of catheter 50, ina deflated state and an inflated state, respectively. Balloon 150preferably includes radiopaque markers 152. Markers 152 inflate withballoon 150 so as to allow imaging of the balloon during inflation, anda determination of whether or not the balloon is in contact with theblood vessel, illustratively shown as the aortic artery AA. Radiopaquemarkers 152 advantageously may be used with any of the balloons devicesdescribed hereinabove.

[0085] Referring now to FIGS. 10A and 10B, further alternativeembodiments of apparatus of the present invention are described thatrely upon passive perfusion of the renal arteries. In accordance withthis aspect of the present invention, in FIG. 10A stent 160 havingconstricted region 161 is placed in the aortic artery AA proximal to therenal arteries RA to constrict the aorta below the renal arteryjunction, and thereby create a pressure differential across the stent.Stent 160 may be constructed for deployment using known techniques, andmay be, for example, a self-expanding coiled sheet, tubular member orballoon expandable structure.

[0086] Alternatively, for treatment of chronic congestive heart failure,external cuff 165 as shown in FIG. 10B may be placed around the aorticartery AA proximal to the renal arteries RA to constrict the aorta andcreate the pressure differential across the cuff. Cuff 165 preferablycomprises a biocompatible, toroidal balloon. Cuff 165 may be placedusing known techniques and may be inflated during or after placementusing an inflation medium supplied through lumen 166. Applicants expectthat the backpressure created by the constriction imposed by stent 160or external cuff 165 will improve flow rate to the renal arteries andother proximal organs.

[0087] As described hereinabove with respect to the embodiment of FIG.1, all of the foregoing embodiments, may include sensors at relevantlocations to measure pressure or flow related parameters, such as renaland aortic pressure in the system of FIG. 1, or distal and proximalaortic pressures and renal pressure in the system of FIG. 3. Suchmeasurements may then be used to monitor or control perfusion of thekidneys for example, by adjusting the perfusion pressure or blood flowrate.

[0088] One preferred embodiment is shown at FIGS. 11-15. FIG. 11 shows acatheter 211 embodying features of the invention disposed within apatient's aorta 210. The catheter 211 has an elongated shaft 212 havinga proximal end 213 and a distal end 214. The balloon distal end 214 hastwo occlusion balloon, proximal balloon 215 and distal balloon 216,disposed about a portion. Proximal balloon 215 is positioned below thepatient's renal arteries 220, while distal balloon 216 is positionedabove the renal arteries 220. Proximal balloon 215 distal end is about 5cm to about 15 cm from distal balloon 216 proximal end, preferably about5 to about 10 cm. Both proximal balloon 215 and distal balloon 216 arecapable of inflation to about 20 to about 30 millimeters outsidediameter. The catheter distal end 214 also includes a blood inlet 217.Between balloon 215 and 216 is located an archimedean screw pump 218.Screw pump 218 includes a housing 219, a rotor 221 and a seal 222. Theseal 222 may or may not let blood pass. The catheter proximal end 213includes a drive mechanism 223. The drive mechanism may be a DC, AC orpneumatic motor capable of maintaining high speed, about 5000 to about30,000 rpm, and moderate torques for periods lasting at least 20minutes. Also connected to the catheter proximal end 213 are inflationsources 224 and 225 for proximal balloon 215 and distal balloon 216respectively. The screw pump 218 may be controlled automatically by anautocontroller 226, which may also be automated to control the inflationof the proximal balloon 215 and the distal balloon 216.

[0089]FIG. 12 better illustrates the inner workings of catheter 211 atthe catheter distal end 214. A drive shaft 227 is located within mainlumen 228. The drive shaft 227 is connected to the drive mechanism 223on its proximal and, and the screw pump 218 in its distal end. The drivemechanism 223 turns the drive shaft 227, which then turns the rotor 221.Blood enters the catheter 211 through the inlet 217 and travels to thescrew pump housing 219. The rotor 221 turns, causing a pressure increasewithin the housing 219. Blood then exits out the blood outlet 229 at ahigher pressure. As was shown in FIG. 11, the housing is located nearthe renal arteries 220. Therefore, blood exits from the housing 219through blood outlet 229 into the renal arteries 220. More than oneblood outlet may be disposed about the radial face of the catheter shaft212. Blood flows in total at a rate of about 600 ml/min to about 1200ml/min, preferably about 800 to about 1200 ml/min out the blood outlet229 into the abdominal aorta 210. This higher pressure blood then movesthrough the renal arteries 220, which are constricted causing ARF. In analternative embodiment, the seal 222 may allow some blood to pass intothe main lumen 228. An additional blood outlet then may be providedproximal to proximal balloon 215, thereby providing blood to the lowerextremities. This may also be accomplished by providing a blood passthrough lumen in addition to the lumen shown in this embodiment (notshown). As screw pump 218 is causing high pressure blood to exit theblood outlet 229, the proximal balloon 215 and distal balloon 216 may beinflated. The balloons 215 and 216 may also be inflated prior to thescrew pump 218 activation. The inflation source 224 is activated, and aninflation fluid enters inflation lumen 230, which is in fluidcommunication with proximal balloon 215. Either simultaneously or at adesired time, inflation source 225 is activated, sending an inflationfluid into inflation lumen 231, which is in fluid communication withdistal balloon 216. The balloons 215 and 216 inflate against the aorta210 to a final outer diameter indicated in phantom, thereby isolatingthe area surrounding the renal arteries 220. This allows the increasedpressure caused by the pump to be most effective. Higher pressure bloodwill be more likely to enter the renal arteries 220, thereby effectivelyperfusing the constricted renal arteries 220. In embodiments which donot include a blood pass through lumen (not shown) or all blood to flowpast the seal 222, the balloons 215 and 216 may be deflated periodicallyto allow blood flow to the lower extremities, or occlusion may becontrolled such that some blood leaks by the balloons 215 and 216without compromising pressure in the renal arteries 220.

[0090] The drive shaft 227 may be a flexible component to accomplishtorque transmission from the motor to the rotor and overcome anycurvature of the catheter shaft imparted by the vasculature. The driveshaft 227 may be made of a coiled wire or a flexible mandrel or acombination of these, possibly of stainless steel or superelasticnitinol. The drive shaft 227 may be coated with a low friction and hightemperature resistant material such as Teflon. The engagement betweenthe drive mechanism 223 and the drive shaft 227 may be accomplished bymeans of a threaded connection, set screw and collar connection, or asnap fit engagement. The drive shaft 227 may be press fit, welded,threaded, or adhesive bonded to the rotor 221.

[0091]FIG. 13 is a detailed view of the screw pump rotor 221. The rotoris a single helix rotor having a hub 232 and a blade 233. The rotorgenerally is about 1 cm to about 5 cm, preferably about 2 cm to about 4cm long. The diameter of the rotor is about 0.1 inch to about 0.25 inch,preferably about 0.15 inch to about 0.2 inch. The distance on the hub232 between blade 233 turns may be uniform. In some embodiments, thedistance between blade 233 turns is not uniform. In certain embodiments,the rotor is a single helix progressive pitch rotor, and the kick area234 has a greater distance on the hub 232 between blade 233 turns. FIG.14 illustrates an alternative embodiment of the catheter of theinvention, wherein the screw pump 218 is located distal to the distalballoon 216. Blood outlet 229 is still located between proximal balloon215 and distal balloon 216.

[0092] The rotor 221 may be an overall cylindrical component consistingof a helical blade 233 around a hub 232 designed to transfer rotationalmotion of the rotor to translational motion of the blood. 1-5 helicalblade components, preferably 1-3 helical blade components may wrap thehub 232 of the rotor. The hub 232, will be minimized to increase theblood volume capacity between the blades 233. A progressive pitch, orvariable, pitch blade may be used to gradually accelerate the bloodalong the length of the rotor 221. The helix may progress from a highpitch to low pitch configuration the last of which is known as the kickof the blade 234. Maximizing acceleration of the blood while minimizingpossible cavitation or hemolysis within the system is preferred. Therotor 221 may be machined, injection molded, or cast as one component orassembled from multiple parts, such as separate blade and corecomponents. The rotor 221 may be made of metal or plastic. The rotor 221will be encased within a housing designed to confine the travel of theblood to a translational volume exchange. The housing 219 may becylindrical and fit closely with the diameter of the rotor 221. Thehousing 219 and rotor 221 will work together to maximize thetranslational motion of the blood and control the centrifugal forcesimparted on the fluid. The housing 219 may be constructed of a metal orplastic. The housing 219 will be a bearing surface for the rotor blades233 and will be required to withstand the forces and temperaturesgenerated by the rotor 221. It may be a portion of the catheter shaft212 in which the rotor 221 is housed but not a separate componentrequiring connection to the catheter shaft 212. If the housing 219 is aseparate component it may be secured to the catheter shaft 212 by heatfusing, adhesive bonding, chemically welding, or barb fitted. Thehousing 219 of the screw pump 218 will be at least as long as the rotor221 and may taper at either end of the rotor 221 to optimize the intakeand outlet volume of the pumping area.

[0093] The centrifugal force imparted on the blood by the rotor willhelp the blood progress toward the outlet do to its placement along theouter diameter of the catheter. shaft. A backpressure will be createdwithin the central lumen of the catheter to prevent the flow of bloodbeyond the outlet. This backpressure will be created either by a o-ringtip seal between the central lumen ID and drive shaft or by apressurized fluid flow within the annular space between the drive shaftand catheter ID. This fluid will also serve to reduce temperaturescreated by the spinning components. The fluid may be saline or dextroseand may be heparinized.

[0094] Another preferred embodiment is disclosed in FIGS. 16-19. FIG. 16shows a catheter 311 embodying features of the invention placed within apatient's aorta 310. The catheter has a shaft 312, a proximal end 313and a distal end 314. Shaft 312 may include markers along the length toassist a user in proper placement. (not shown). Such markers areespecially helpful along the proximal end 313, to aid in placementwithout the use of X-ray fluoroscopy guidance. The distal end 314includes a distal tip portion 315. Distal tip portion 315 is placedabove the patient's renal arteries 320. The distal end 314 additionallyincludes an inflatable balloon 316. Inflatable balloon 316 is placedbelow the patient's renal arteries 320. Inflatable balloon 316 is about5 cm to about 20 cm from the distal tip portion 315, preferably about 10cm to about 15 cm. The distal tip portion 315 includes discharge ports317. Discharge ports may be formed of slits. In an alternativeembodiment illustrated in FIG. 17, the discharge ports 317 are sideholes338, placed along a pigtail shaped distal tip portion 339 with a taperedclosed tip 340. If the distal tip portion 315 of the catheter 311 isclosed, it may be sealed or include a sealing surface which mated withan obturator or a stiffening mandrel. In such an even, it may becomenecessary to use a duck-billed valve to provide for guidewire passagewithout losing the fluid seal.

[0095] The proximal end 313 is connected to a system console 318. Thesystem console 318 includes an inflation source 321 and a drug deliverysource 322. Inflation source 321 is in fluid communication withinflation lumen 323. An inflation fluid travels through inflation lumen323, which is in fluid communication with the inflatable balloon 316,and inflates inflatable balloon 316. Drug delivery source 322 is influid communication with drug delivery lumen 324. A drug may beintroduced into the drug delivery lumen 324 and travels to the distaltip portion 315. At the distal tip portion 315, the drug delivery lumen324 is in fluid communication with the discharge ports 317, therebydischarging the drug into the patient's aorta 310. In alternativeembodiments, the catheter 311 additionally includes a blood pass throughlumen 325. The blood pass through lumen 325 will have an inlet port onthe distal tip portion 315 (not shown) and an outlet situated on thecatheter proximal to the balloon (not shown) to supply blood to thelower extremities during balloon inflation.

[0096] The systems console 318 additionally includes an autocontroldevice 319. An example of such an autocontrol device would be amicroprocessor-control module with a user interface. FIG. 20 illustratesthe benefit of including an autocontrol device 319 in the system console318. The balloon 316 may be inflated periodically to correspond to drugdelivery. Therefore, the drug will be directed into the patient's renalarteries 320 because the balloon 316 has isolated the renal arteries320. This allows for a localized delivery of a drug to the renalarteries 320 without having a system-wide effect on the patient's body.A preferred drug for this apparatus would include a drug which is ashort-acting vasodilator.

[0097] As illustrated in FIG. 20, the delivery of the drug will bysynchronized with the aortic occlusion to divert the blood flow andinfused drug to the renal arteries. The time lag between the beginningof balloon inflation and the beginning of drug infusion in a cycle iscalled T1. The lag time between the end of drug infusion and balloondeflation is called T2. The balloon will occlude the aorta in order todeliver a high amount of drug to the renal arteries, and only a minoramount to the lower extremities. The therapy will be automated to keepthe drug level in the renal arteries at a set minimum to ensureincreased renal perfusion is sustained. The drug may be delivered inincreasingly small amounts, as well, as therapy progresses and thereduce the patient's risk of systemic effects of too much drug.

[0098] While preferred illustrative embodiments of the invention aredescribed above, it will be apparent to one skilled in the art thatvarious changes and modifications may be made therein without departingfrom the invention, and the appended claims are intended to cover allsuch changes and modifications that fall within the true spirit andscope of the invention. Additionally, although various features of theinvention are disclosed in specific embodiments, one or more of thefeatures may be used and exchangeable in other embodiments disclosedherein.

What is claimed is:
 1. Apparatus for perfusing a kidney in vivo, theapparatus comprising: a catheter having an inlet port, the inlet portconfigured for placement in a source of autologous blood, an outletport, and a lumen in fluid communication with inlet port and the outletport; a first inflatable member disposed on the catheter adjacent to theoutlet port; and a pump that causes blood to flow from the inlet port tothe outlet port, so that blood exiting the outlet port is directed to arenal artery.
 2. The apparatus of claim 1 wherein the outlet port isadapted to be disposed within the renal artery and the first inflatablemember retains the outlet port in the renal artery.
 3. The apparatus ofclaim 1 further comprising a second inflatable member, wherein theoutlet port is disposed between the first and second inflatable members,and the first and second inflatable members are adapted to isolate aregion of the aorta when inflated.
 4. The apparatus of claim 1 whereinthe lumen includes an inlet lumen coupled to the inlet port and anoutlet lumen coupled to the outlet port, wherein the inlet lumen iscoupled to an inlet of the pump and the outlet lumen is coupled to anoutlet of the pump.
 5. The apparatus of claim 1 further comprising anoxygenation element coupled between the inlet port and the outlet portof the catheter.
 6. The apparatus of claim 1 wherein the pump includes apiston and shaft that reciprocate, reciprocation of the piston and shaftalternately causing blood to be drawn into the lumen through the inletport and expelled from the lumen through the outlet port.
 7. Theapparatus of claim 4 further comprising one or more one-way valves thatpermit blood to flow only from the inlet port to the outlet port.
 8. Theapparatus of claim 1 wherein a first portion of the catheter is adaptedto be disposed through either a patient's femoral artery or upper aorticartery and a second portion of the catheter is adapted to be disposed inthe patient's aorta through the contralateral femoral artery.
 9. Theapparatus of claim 1 further comprising radiopaque markers disposed onany of the first and second occlusion balloons and the center balloon.10. The apparatus of claim 1 wherein pump further comprises controlcircuitry that adjusts operation of the pump responsive to a preselectedmeasured parameter.
 11. Apparatus for perfusing one or more kidneys invivo comprising: a catheter having first and second inflation lumens;and first and second occlusion balloons coupled in fluid communicationto the first inflation lumen; a center balloon coupled in fluidcommunication to the second inflation lumen; and a valve for selectivelycoupling the first and second occlusion balloons to the first inflationlumen or coupling the center balloon to the second inflation lumen; anda pump coupled to the valve.
 12. The apparatus of claim 11 furthercomprising a controller that first causes the pump to inflate the firstand second balloons to trap an amount of blood, and then causes the pumpto inflate the center balloon.
 13. Apparatus for enhancing perfusion ofa patient's kidneys, the apparatus comprising: a stent having aconstricted region, the stent adapted to be placed in the aorta at alocation below the patient's junction to the renal arteries. 14.Apparatus for enhancing perfusion of a patient's kidneys, the apparatuscomprising: a cuff having a constricted region, the cuff adapted to beplaced around the aorta at a location below the patient's junction tothe renal arteries.
 15. A method of enhancing perfusion of a patient'skidney in vivo, the method comprising: providing a catheter having aninlet port, an outlet port, a lumen there between, a first inflatablemember and a pump; inserting the catheter through the patient's aorta sothat the outlet port is disposed in a renal artery; inflating theinflatable member to retain the outlet port in the renal artery;disposing the inlet port in a source of autologous blood; coupling thepump to the catheter; and activating the pump to cause blood to flowfrom the inlet port to the outlet port.
 16. The method of claim 15wherein coupling the pump to the catheter comprises coupling the pumpbetween the inlet port and the outlet port.
 17. The method of claim 15wherein the pump includes a piston and shaft that reciprocate andactivating the pump comprises reciprocating the piston and shaftalternately to cause blood to be drawn into the lumen through the inletport and expelled from the lumen through the outlet port.
 18. The methodof claim 17 wherein catheter further comprises one or more one-wayvalves and activating the pump further comprises activating the pumpfurther comprises permitting blood to flow only from the inlet port tothe outlet port through the one or more one-way valves.
 19. The methodof claim 15 further comprising: measuring a flow-related parameter; andadjusting operation of the pump responsive to the measured flow-relatedparameter.
 20. The method of claim 15 further comprising oxygenatingblood flowing between the inlet port and the outlet port.
 21. A methodof enhancing perfusion to a patient's kidney in vivo, the methodcomprising: providing a catheter having an inlet port, an outlet port, alumen there between, first and second inflatable members and a pump;inserting the catheter through the patient's aorta so that the outletport is disposed in the patient's aorta; inflating the first and secondinflatable members to isolate a region of the aorta including thepatient's junction to the renal arteries; disposing the inlet port in asource of autologous blood; coupling the pump to the catheter; andactivating the pump to cause blood to flow from the inlet port to theoutlet port.
 22. The method of claim 21 wherein coupling the pump to thecatheter comprises coupling the pump between the inlet port and theoutlet port.
 23. The method of claim 21 wherein the pump includes apiston and shaft that reciprocate and activating the pump comprisesreciprocating the piston and shaft alternately to cause blood to bedrawn into the lumen through the inlet port and expelled from the lumenthrough the outlet port.
 24. The method of claim 21 further comprisingoxygenating blood flowing between the inlet port and the outlet port.25. A method of enhancing perfusion to a patient's kidneys in vivo, themethod comprising: providing a catheter having first, second and thirdballoons, the third balloon disposed between the first and secondballoons; placing the catheter in the patient's aorta so that the firstand second balloons straddle a region of the aorta including thepatient's junction to the renal arteries; inflating the first and secondballoons to trap an amount of blood within the region and isolate theregion; inflating the third balloon to direct the trapped blood into therenal arteries.
 26. The method of claim 21 further comprising deflatingthe first, second and third balloons to re-establish blood flow throughthe aorta.
 27. A method for enhancing perfusion of a patient's kidneys,the method comprising: providing a stent having a constricted region;and deploying the stent in a patient's aorta at a location below thejunction to the renal arteries to create a backpressure in the aorta.28. A method for enhancing perfusion of a patient's kidneys, the methodcomprising: providing an inflatable cuff; surgically placing theinflatable cuff around a patient's aorta at a location below thejunction to the renal arteries constricted region; and inflating theinflatable cuff to create a backpressure in the aorta.
 29. An apparatusfor perfusing a patient's kidneys with blood, comprising: an elongatedcatheter shaft having a first end, a second end, a blood inlet port, ablood outlet port, and at least one lumen extending between the bloodinlet port and the blood outlet port; an in-line blood pump; and atleast one expandable member proximate to the second end which has anexpanded configuration which secures the expanded expandable memberwithin the abdominal aorta.
 30. The apparatus of claim 29 wherein thein-line pump is an archimedean screw pump.
 31. The apparatus of claim 29comprising at least two expandable members longitudinally displaced fromone another along the catheter shaft.
 32. The apparatus of claim 31wherein the blood outlet port is located between the two expandablemembers.
 33. The apparatus of claim 31 wherein the in-line blood pump isan archimedean screw pump and the archimedean screw pump is located at atransverse location between the two expandable members.
 34. An apparatusfor locally delivering a drug to a patient's kidney comprising: anelongated catheter shaft having a first end, a second end including atleast one discharge port, and at least one lumen in fluid communicationwith the discharge ports; a drug source; and at least one expandablemember proximate to the second end which has an expanded configurationwhich secures the expanded expandable member within the abdominal aorta.